Effect of Ambient Gas Properties for Characteristics of Non-Reacting Diesel Fuel Spray

In this paper, spray characteristics were examined to deduce the effect of ambient gas properties. Considered ambient properties were the viscosity μ_a and density ρ_a, and thus the kinematic viscosity ν_a. The objective of this paper is to reveal the effect of compressibility of the ambient gas to spray formation. In the experiments, the changed ranges were And a standard-sac volume nozzle of hole diameter d_n =0.25 mm (l_n/d_n=3.0) was used at constant injection pressure difference (Δp=16.2 MPa). Also the injection pressure was varied in the range of 55 to 120 MPa with a mini-sac volume nozzle of hole diameter d_n =0.20 mm (l_n/d_n =5.5). Several different gases were used to change the ambient viscosity at a room temperature. From the experiments, it is obtained that larger the viscosity, the more the spray spreads in the radial direction, thus the spray angle gets larger and the tip penetration became shorter. And atomized droplets become smaller with larger ambient viscosity at the same density. It is concluded that the kinematic viscosity should relate to the phenomenon of diesel fuel spray under different ambient conditions.